In the refurbishment or repair of subterranean pipelines it is the common practice to coat the interior pipe walls with a coating of mortar. This is usually achieved by passing a rotating dispersion head through the pipe for spraying the mortar onto the interior pipe walls followed by a trowel which is concentrically located in the pipeline for engaging and smoothing the mortar while still in a plastic condition to insure a uniform coating and a smooth interior surface. The trowel is designed with an outer diameter that corresponds to the inner diameter of the coated pipe walls to insure a smooth, consistent coating for the entire length of the pipeline. However, when the diameter of the interior wall of the pipe varies along the length of the pipe, due to corrosion, the buildup of impurities or the like, the trowel will become oriented in an eccentric relation with the pipeline, and may even jam in the pipeline.